I am renting a house that has no central air, instead we have to use window units. There is evidence that the house used to have a gas heater, and there is a 2 foot by 3 foot hole in the floor leading to the crawlspace beneath the house with a grate placed over it. The landlord said she won't cover it, because it is for ventilation. Is this hole still necessary, or can I cover it up?
Repair and Ventilation – Can a Vent Leading to Crawlspace Be Covered?
crawlspacerentalrepairventilation
Related Solutions
There's a number of things you could do, this is one I would do in your situation. These fans are made to fit inside sheet metal ducts. Go ahead and get 2 lengths of this stuff. You will end up with a joint somewhere in the room, but then the duct can run fully through both walls and there's enough slop in the fit that precise cutting is not needed.
Because of the joint, you will need a hanger support that anchors into the ceiling, which I assume is concrete. You would need a hammer drill to make the hole necessary to insert an anchor stud to which the hanger can be attached.
This is not the most attractive thing in the world, but it can be painted so that it's not too objectionable. Painting exposed ductwork is done intentionally sometimes as a desirable (to some) "look". You could also construct a soffit box to contain the duct, you end up with a sort of stair step on the ceiling. Given the extra work for this, it's easier to like the painted duct look.
To fill in the holes, get some cement backer board and cut to the size of each opening. Also cut holes to fit the duct or fan. For the size involved, the boards can just be glued in place with construction adhesive. You can also glue in some backup cleats behind the boards to increase the glued surface area if you like. The boards should be recessed about 15mm from the wall surface. The remaining space is filled with portland cement plaster in 2 or 3 coats. It is an obvious patch, but it sort of matches the wall and would be hardly noticeable if the walls are to be painted.
Critters can squeeze their bodies into any space their head will fit into.
Humans, not so much.
There are ways to fix and exit using flexible mesh that allows them to leave, but not return.
I watched one of those exterminator tv shows years ago and saw their setup. It was ingenious. You may find an episode or explanation on YouTube.
We had a turd of a neighbor kid who got mad at us and dumped her pet rats over our fence. The havoc they caused was a six-month battle of wills but I prevailed and they never got inside the house.
Glue traps are great if your a cold hearted so and so like me who doesn't lose sleep when they start screaming after they get stuck and before their nose does, suffocating the buggers. My husband couldn't handle it. So I had to go with snap traps.
Broke both thumbs and two fingers, but I got them put out. And replaced daily as the body count rose.
I suggest peanut butter. Just enough to coat the trigger mechanism, though. They are not stupid creatures and will steal your bait every chance they get.
For the bigger Norwalk rats, I used live traps and had a slick-sided barrel with enough water to make them have to swim...until they couldn't.
Check with your local animal shelter. They often have these things that you can borrow after leaving a refundable deposit to cover the trap should you not return it.
Again, unless you are willing to kill these things, you will never win the battle.
In the meantime, start putting steel wool in any opening you find and firmly attach metal mesh or sheet metal on both sides of the opening. Yes any left inside the barrier will die. And smell to high heaven. But you have to stop the flood in before you have a chance of beating the stragglers down.
Also, clean up anything that could be food. Secure wiring and check the insulation on any exterior wiring. They love that stuff.
If you have a zoo close by, see if they will let you buy lion or tiger poop. It will stop just about anything from coming around. And it stinks... it is poop... but you have to use everything available to win this war.
As an aside, steel wool in your weep holes, should you have any, will also help stop hornets and wasps (or bees) from entering there and nesting in your walls. Just replace it regularly as it does degrade.
Good luck. Put your game face on. This one is not for the weak willed.
Best Answer
If that grate-covered hole is in a "common area" and up against a wall, you can bet that it was once a floor furnace. The combustion boxes on older gas floor furnaces would crack over time (decades) and become a carbon monoxide (CO) danger to inhabitants due to flue gas escaping into the home instead of going up and out the vent pipe. A utility inspector would red-tag (forbid the use of) the furnace when a new renter called for assistance with lighting the pilot light. Instead of replacing the unit, the landlord takes the easy way out and removes it, patching the wall above but with no easy way of repairing the hole in the floor. I have seen this exact scenario before.
To confirm, go up in the attic and see if there is an old vent pipe above the general area. If so, then go ahead and cover up that unneeded "ventilation" hole. It probably allows a musty smell in the house anyway. Do not disturb the old vent pipe if it appears to be something other than metal, it may be Transite pipe, which contains asbestos (a carcinogen).
Make sure there is really no functioning heating equipment down there before you cover it up (fire hazard). Your gas supply utility will send a technician to confirm for free if you tell them you have a safety concern.